Filter out 'unpushed' updates along with 'obsolete' and 'deleted'
    
    There are several places where we ignore updates that are
    obsolete or deleted. In all of these places we should similarly
    ignore updates that are 'unpushed' - in modern Bodhi this is
    roughly the equivalent of 'deleted', you can't really delete an
    update any more, if it's really bad and you want it to go away
    you 'unpush' it. This should solve the problem of the unpushed
    update FEDORA-2019-be95719373 showing up in Fedora 31 candidate
    compose requests.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>